The unique advantage of the S-band Electron Spin Echo spectroscopy in achieving exact cancellation is used to determine quadrupole coupling constants of N-14 in substituted aromatics. In frozen solutions of nitro-aromatic compounds, the weakly-coupled nitrogen nuclei produce S-band ESEEM patterns which yield well-defined peaks in the frequency domain. This work provides a critical test of predictions made by Professor Singel. This is a continuing project.